The n term of an A.P is 7n-5,find the sum of first 20 terms of the series.

The nth term of an A.P. is 7n-5, find the sum of first 20 terms of the series.

The sum of the first p terms of an A.P. is q and the sum of the first q terms of the same A.P. is p. Find the sum of the first (p+q) terms of the A.P.

The nth term of a series is 3^(n) + 2n , find the sum of first n terms of the series.

The sum of first ten terms of an A.P. is 155 and the sum of first two terms of a G.P. is 9. The first term of the A.P. is equal to the common ratio of the G.P. and the first term of the G.P. is equal to the common difference of the A.P. Find the two progressions.

The nth term of an A.P. is p and the sum of its first n terms is q. Prove that its first term is (1)/(n)(2q-p n) .

The sum of the 1st m terms of an AP is n and the sum of the 1st n terms of the same AP is m. Find the sum of the 1st (m + n) terms of the AP.

The rth term of a series is (2r + 1)2^(r ) , find the sum of first n terms of the series.

If the nth term of a series be (2.3^(n-1) + 1) , find the sum of first r terms of the series.

The twelfth term of an A.P. is (-13) and the sum of its first four terms is 24, find the sum of first 10 terms of the A.P.

Find the sum of first n terms of 1+3+7+15+31+….